1. Field of the Invention
The present invention relates to a fire stop valve which is formed by a member composed of a frame and a tunnel, in which a butterfly damper is mounted for pivoting about an axis between a closed position restoring the fire retardant rating of a wall or a panel and an open position called the standby position.
2. Description of the Related Art
There are many types of fire stop valves which are generally of complex construction in order to be able to withstand the temperatures and pressure differences imposed by some regulations. The complexity of existing valves is made necessary by their structure itself, which transmits the increase of temperature in the chamber to be isolated from the exterior, bringing about expansions, and deformations reducing the fluid-tightness of the valve in the closed position.